My account is partially suspended because of an authenticity complaint for a used book. Amazon keeps demanding an invoice from a supplier to prove the book's authenticity. I don't have an invoice for this book (I bought it at a thrift store,) and all communications with Amazon result in repeated demands for an invoice.

On this page: https://sell.amazon.com/learn/how-to-sell-books, Amazon states the following:

Step 1: Decide how you want to source books

There are multiple ways to source books for resale. The simplest way is to sell books you already own. But you can also build your inventory through the following channels:

Wholesale: Buy books in bulk online or at bookstore closings for lower prices. You can also procure new books in larger quantities from distributors or publishers. You may not have total control over what you get, but you can get more books at wholesale costs.

Local sources: Find used books by browsing local library book sales, used bookstores, yard sales, and thrift shops.

Auctions: Seek out auctions, estate sales, or farm sales with used or collectible books.

Amazon is encouraging people to buy used books at thrift stores that do not provide itemized invoices, and then suspending those same users for not having invoices. Why am I being punished when Amazon's policies are contradictory?